Aluminum wheels

[olly hondro]

Having zero threads sticking out weakens the fastened joint. Without protruding material to provide a backstop for the last couple threads of engagement, forces put against those last threads just roll them over off the end of the bolt.

Minimum Threads Protruding Beyond Nut

A minimum thread protrusion length is given to ensure that all the threads are engaged. This is required to ensure a full-strength fastener. Equipment component drawings should specify the type, length, and size of bolt, stud, bolt-stud, etc. to be used to obtain the proper thread protrusion.

www.engineersedge.com

I will have to think about that. Ensuring the fastener is engaged, backstopping, and the "feel good" of visual confirmation. There is some good physics in there somewhere.